You need to register it the day it becomes applicable to you. As procedural law is retrospective

Dear Sir,

The said partition is valid even if not registered. 

It should be dissolved by providing equal sharing ratio to all members of HUF. and registered it will registrar. So now it invalid.

Deed of partition for division of property is required to be stamped and registered 

Dear Sir,

There may be difference of opinions but there is no such cut off date

4 months from execution you need to register it. Otherwise you may attract penalty to register

No unless ot is registered it is not valid.

Section 17(1)(b) of the Registration Act lays down that a document for which registration is compulsory should, by its own force, operate or purport to operate to create or declare some rights in immovable property.

2)

if the writing itself effects a division, it must be registered. See: Rajangam Ayyar v. Rajangam Ayyar, LR (1923) 69 IA 123 and Nani Bai v. Gita Bai, AIR (1958) SC 706. It is well-settled that the document though unregistered can however be looked into for the limited purpose of establishing a severance in status, though that 

severance would ultimately affect the nature of the possession held by the members of the separated family as co-tenants.

Registration of partition is mandorrty from long time even before 1988 but a mere family arrangement not compulsorily registrable.

Unregistered partition deed is invalid. 

On the dissolution of HUF, property partitioned automatically and oral partition is valid. Only if reduced in writing than registration is must. 

- If the partition was written through family settlement , then it is not required to be registered, but if Partition deed was written , then it must be registered after paying the stamp duty , otherwise it is an invalid Partition. 

Unregistered documents are invalid

The partition deed if effected amongst family members is valid and enforceable even if not registered.

Registration can be done but it is not compulsory.

Partition of HUF can be done through family settlement or through partition deed. Stamp duty is not required for family settlement and thus is not required to be registered, whereas partition deed attracts stamp duty and must be registered. 

Registration of HUF agreement is not mandatory. Even on the basis if a plain agreement on a steam paper is enough for this.

Similarly partition is can be validly done orally. However if it is put into writing then it is to be compulsorily registrable.

The partition of property whether HUF or otherwise shall be legally valid only when it was drawn by a registered deed.

Until and unless there is no dispute among the coparceners  about this partition, there may not exist any problem, however you may decide about the validity based on the existing circumstances, but please note that unregistered partition deed is not recognised as legally valid.

Oral partitions among the cosharers are held valid as per law.

Subsequent entries in the books of account are good evidence of partition. The Bombay High Court in the case of CIT vs. Shiolingappa Shankarappa Mendse and Bros. [1982] 135 ITR 375 (Bom.) had occasion to deal with a case where there was a partition of HUF and subsequent formation of a partnership firm by the erstwhile members of the HUF. Transaction of partition was evidenced by book entries. Partnership was held valid.

The HUF, which has been hitherto assessed, must make a claim to the assessing officer that the HUF properties have been subjected to total partition.

The Assessing Officer will make an inquiry in to the claim after giving notice to all members of the HUF and if he is satisfied that the claim is correct, he will record a finding that there was a total partition of the HUF and the date on which it has taken place.

1. It is mandatory to register Partition deed to make it valid as per law.

2. Partition deed without registration will not be considered valid.

3. HUF property cannot be partitioned without dissolution of HUF.

1. It has always been mandatory ever since Registration Act was enacted.

2. It was mandatory in 1988 as well.

1. As per the information mentioned in the present query, makes it clear that you have been contrary been given the date of its mandate in nature, but not been apprised about the situation where only undisputed possession matters in separation and nuclear possession.
2. I would like to apprise you that partition even on a simple paper without it’s been registered is also valid in the ways of law if by virtue of the same, parties are residing or enjoying the property since long.
3. And in your case, you have the long possession as per the above language of the query.
4. So, can further seek my advice more precisely if wish to in order to remove your further confusion.